The present disclosure, in some embodiments thereof, relates to pulmonary delivery of a substance using a personal inhaler device and, more particularly, but not exclusively, to controlling flow through an inhaler.
U.S. Pat. No. 5,655,520 teaches “A nebulizer is improved by placing a flexible valve in the ambient air inlet tube. Inhalation suction and Venturi effect shut down the flexible valve in proportion to the strength of the inhalation. Thus, the same output flow rate is obtained even with variable strength inhalations. Medications can be properly administered by controlled inhalation flow rates. In an alternate embodiment a metered dose inhaler (MDI) is outfitted with a similar flexible valve. Once again the patient is forced to inhale at a constant flow rate, thus causing the medication to seep deeply into the lungs. In both embodiments the flexible valve is preferably shaped in a duck billed fashion with air flow flowing toward the narrow end of the duck bill.”